Acrylic tank humidity/heating pad issues

Question
I recently bought an acrylic 112 gal tank for my 4.5' ball python. It appears he thrives in his new environment. however I am having issues with humidity and heating pads. I have noticed that acrylic does not disperse the heat from the pad like glass, it seems to hold it at it's hottest point, I do not want to burn my snake but without it the humidity drops secondary to only using heating bulbs which keep his warm side at 80-85 and his cool side at 70 but suck the humidity out of the tank....I have researched many options from human heating pads to ceramic tiles over heating pads to help disperse the heat ? I am stumped and want the best for him as I adopted him from someone who had no knowledge on how to care for him. HELP !

Answer
Jenn,
  I see your problem. I suggest that you put a large water dish directly over the heating pad. It will help disperse the heat and increase the humidity. A ceramic water dish would be best, anything plastic will not absorb and pass on the heat.